python data_error ai_generated true

fastapi.exceptions.RequestValidationError: 422 Unprocessable Entity

ID: python/fastapi-request-validation-error-missing-field

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-01-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

Request body or query parameters do not match the expected Pydantic model schema, such as missing required fields or incorrect types.

generic

中文

请求体或查询参数与预期的Pydantic模型架构不匹配，例如缺少必填字段或类型错误。

Workarounds

  1. 95% success 
    Define a custom exception handler: @app.exception_handler(RequestValidationError)\nasync def validation_exception_handler(request, exc):\n    return JSONResponse(status_code=422, content={"detail": exc.errors()})
  2. 85% success 
    Use Pydantic's Field(..., description='...') to document requirements and ensure clients send correct data.

Dead Ends

Common approaches that don't work:

  1. 60% fail

    Catching the exception globally and returning a generic 400 hides the specific field issues, making debugging harder.

  2. 80% fail

    Disabling validation with model_config = {'extra': 'allow'} can allow invalid data through, causing downstream errors.